When I flush my toilet the cistern seems to struggle with filling up because so much water continues to flow into the toilet bowl and I don't know why.

I've removed the cistern top and pulled the red handle on the ball-cock and that stops the flow of water into the bowl, but only whilst I hold it.

However, interestingly the flush button seems to go loose after each flush, kind of like it becomes unconnected and the only way I can get the flow of water into the bowl to stop and the cistern to fill again is to pull off the cistern lid and constantly push on the flush button until I feel a bit of tension go back into the button. Then the cistern fills up fine with no problems and the water stops leaking into the bowl.

Does anyone have any idea what is wrong with it?

  • 2
    Would help if we knew what kind of toilet internals we're talking about. Is the flap sticking? – isherwood Jul 25 '19 at 14:45
  • Did you ever get this resolved? If so, please give a check-mark to the answer that helped you the most, or write up your own answer explaining what you did to get it fixed and give yourself a check mark. That will help others with this kind of problem know that this has a resolution and is a good place to look for their answer. – FreeMan Aug 19 '20 at 12:28

Not knowing the specifics of your flush and valve system, I can only answer generally.

The fill-valve stops the inflow of water when some sort of sensor, typically an actual float, reaches a certain level of height either operating the fill valve to halt the ingress of water and usually ending the flush cycle, or it may in some way signal another part (unusual) to cease the water flow and end the flush cycle.

Most commonly a ‘flapper valve’ is physically lifted off of its ‘seat’ allowing the water in the tank to rush down into the bowl. Then the ‘float’ which operates the fill valve lowers until the valve opens, allowing water in to refill the tank. After the water exits the tank, the flush valve (or flapper) must lower onto its valve seat and re-seal the tank allowing it to re-fill ready for the next operation (or flush.)

If all of this only happens when you work the correct part manually (removing the cover and pressing with your finger) then one of two things are needed to restore correct operation (generally,)

  1. You may be able to adjust some part of the mechanism to make it flush and re-fill as designed, stopping the fill operation at the correct level of water in the tank and not continue filling and possibly leaking water, usually into the tank. In many toilets the float may need replacement or adjustment. In many the fill valve components may need repair, adjustment or replacement. Often the flapper valve needs repair or adjustment - it may no longer be attached correctly, or the valve seat seal may be worn orobstructed.

  2. In fill mechanisms with a single piece construction you may need to repair, adjust or sometimes replace that entire mechanism.

Either call a plumber or identify the type of mechanism, figure its mode of operation, and then try to determine where the fault occurs in its cycle. Without this info best we can do is guess!


"constantly push on the flush button until I feel a bit of tension go back into the button" (I've never worked on one with buttons) that's called jiggling the handle. That's what you have to do when the flapper doesn't seat right every time anymore. (replace flapper)

There should be a hose feeding into the overflow tube. Does the hose have a clamp on it for restricting the amount of water it dumps down it? (increase restriction. A less desirable option is to disconnect it from the tube)

Is the valve's float set so that tank level anywhere near overflowing into the tube doesn't happen? (decrease tank 'fill' level; lower the valve float)

Also, could be the chain float is way too low. (raise the chain float)

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